The present invention generally pertains to wireless networks, and more particularly to methods for internetworking between such networks.
Computer networks allow multiple computers, peripherals and other information storage, retrieval or processing devices to share data. Each device attached to a network is typically referred to as a node on the network, or a node that is part of the network. Local Area Networks (xe2x80x9cLANsxe2x80x9d) have historically consisted of nodes interconnected by physical telecommunications media (eg, coaxial cable, twisted pair wire, or fiber optics). Recently wireless LANs, the nodes of which are not connected by means of a physical medium, have started to appear in the market. These wireless LANs communicate by means of infra-red (IR), radio or other signals. One of the benefits of using wireless LANs is that cabling is not required. This is a particularly useful feature for mobile nodes such as laptop and notebook computers, PDAs (personal digital assistants), and the like. If appropriately equipped with an appropriate wireless adapter, the mobile nodes can move around within a predefined coverage area and remain connected to the network.
One method of implementing a wireless LAN is similar to a cellular phone network system. In this method wireless mobile nodes do not communicate directly with each other, but rather send all signals to a central base station, which then redirects the signals to the destination node. In certain systems of this type each wireless mobile node is allowed to simultaneously participate in different wireless networks. However, current approaches do not provide for communication between wireless nodes of different wireless LANs, even though both such nodes may be in range of a third wireless node included within both networks.
In a xe2x80x9cpeer-to-peerxe2x80x9d wireless LAN, data packets transmitted by a node are received by all nodes within range. Packets are ignored by all nodes except those to which the packets are addressed. This parallels the packet delivery systems of such wired LAN protocols as Ethernet. However, the limited range of wireless nodes makes it much more difficult to implement a wireless, in lieu of a wired, peer-to-peer wireless LAN. For example, in a peer-to-peer wireless LAN it cannot be guaranteed that each node of a given network is capable of listening to all network traffic. That is, certain nodes may become xe2x80x9chiddenxe2x80x9d from others when moved outside of existing coverage areas.
In view of the constraints on transmission range applicable to both peer-to-peer and other types wireless LANs, it would be desirable to facilitate communication between the nodes of distinct wireless LANs. However, any implementation affording such xe2x80x9cinternetworkedxe2x80x9d communication capability would need to overcome a number of difficulties. For example, the high mobility, limited range, and power-saving features (e.g., sleep modes) characterizing many devices served by wireless LANs tend to limit the awareness of such devices to significant network events. The high mobility of many such devices also complicates the process of identifying the location of a desired partner communication device within a neighboring wireless LAN.
Briefly, therefore, this invention provides for a method and apparatus for internetworked communication. The present invention includes first and second wireless networks containing first and second pluralities of wireless nodes, respectively. In a preferred embodiment an internetworking node participates in both the first and second wireless networks, and receives a first set of network information relating to the first wireless network from the first plurality of wireless nodes. The first set of network information identifies each of the first plurality of wireless nodes and the services offered thereby. The internetworking node is configured to transmit the first set of network information to a master node of the second wireless network. In a preferred embodiment the internetworking node receives, from the second wireless network, a second set of network information identifying each of the second plurality of wireless nodes and the services offered thereby. The internetworking node may also transmit the second set of network information to a master node of the first wireless network.
The first master node may be configured to broadcast information relating to the services offered by each of the first plurality of wireless nodes and the second wireless network. Likewise, the second master node may be configured to broadcast information relating to the services offered by each of the second plurality of wireless nodes and the second wireless network. In a preferred embodiment each of the first plurality of wireless nodes transmits an advertisement to the first master node specifying its address and services offered thereby. Similarly, each of the second plurality of wireless nodes transmits an advertisement to the second master node specifying its address and services offered thereby. The first and second master nodes store information from each received advertisement within first and second network resources tables, respectively. This enables a wireless node from the first network to obtain services from the second wireless network, and vice versa, by way of the internetworking node. In a preferred implementation the internetworking node only advertises the services available within the first or second wireless networks to the extent it currently possesses sufficient bandwidth to support provision of such services to nodes within the other wireless network.
In an alternate embodiment the first and second wireless networks do not share a common internetworking node, but may communicate through an interconnection network operatively connected to at least one node of each network. The connected node of the first wireless network issues an advertisement which includes a description of the services offered by the second wireless network, and the connected node of the second wireless network issues an advertisement which includes a description of the services offered by the first wireless network. The first and second master nodes store information from each received advertisement within first and second network resources tables, respectively.